Technical Field
[0001] The present invention relates to a refrigerant compressor for use with a refrigerator,
an air conditioner, or the like, and a refrigeration device including the refrigerant
compressor.
Background Art
[0002] In recent years, for the purpose of global environment conservation, a refrigerant
compressor with a higher efficiency, which can reduce the use of fossil fuel, has
been developed.
[0003] One approach for achievement of the higher efficiency of the refrigerant compressor
is, for example, formation of a phosphate coating film on a slide surface of a slide
section such as a piston or a crankshaft to prevent abrasion of the slide section.
By forming this phosphate coating film, unevenness of the processed surface of a machine
processing finish can be removed, and initial conformability between slide members
can be improved (e.g., see Patent Literature 1).
[0004] Fig. 13 is a cross-sectional view of a conventional refrigerant compressor disclosed
in Patent Literature 1. As shown in Fig. 13, a sealed container 1 is an outer casing
of the refrigerant compressor. Lubricating oil 2 is reserved in the bottom portion
of the sealed container 1. The sealed container 1 accommodates therein an electric
component 5 including a stator 3 and a rotor 4, and a reciprocating compression component
6 driven by the electric component 5.
[0005] The compression component 6 includes a crankshaft 7, a cylinder block 11, a piston
15, and the like. The configuration of the compression component 6 will be described
below.
[0006] The crankshaft 7 includes at least a main shaft section 8 to which the rotor 4 is
pressingly secured, and an eccentric shaft 9 which is provided eccentrically with
the main shaft section 8. The crankshaft 7 is provided with an oil feeding pump 10.
[0007] The cylinder block 11 forms a compression chamber 13 including a bore 12 with a substantially
cylindrical shape and includes a bearing section 14 supporting the main shaft section
8.
[0008] The piston 15 is loosely fitted into the bore 12 with a clearance. The piston 15
is coupled to the eccentric shaft 9 via a connecting rod 17 as a coupling means by
use of a piston pin 16. The end surface of the bore 12 is closed by a valve plate
18.
[0009] A head 19 is secured to the valve plate 18 on a side opposite to the bore 12. The
head 19 constitute a high-pressure chamber. A suction tube 20 is secured to the sealed
container 1 and connected to a low-pressure side (not shown) of a refrigeration cycle.
The suction tube 20 leads a refrigerant gas (not shown) to the inside of the sealed
container 1. A suction muffler 21 is retained between the valve plate 18 and the head
19.
[0010] The main shaft section 8 of the crankshaft 7 and the bearing section 14, the piston
15 and the bore 12, the piston pin 16 and the connecting rod 17, the eccentric shaft
9 of the crankshaft 7 and the connecting rod 17 constitute slide sections.
[0011] In a combination of the iron-based materials among the slide members constituting
the slide sections, as described above, an insoluble phosphate coating film comprising
a porous crystalline body is provided on the slide surface of one of the iron-based
materials.
[0012] Next, the operation of the sealed compressor having the above-described configuration
will be described. Electric power is supplied from a power supply utility (not shown)
to the electric component 5, to rotate the rotor 4 of the electric component 5. The
rotor 4 rotates the crankshaft 7. By an eccentric motion of the eccentric shaft 9,
the piston 15 is driven via the connecting rod 17 as a coupling means and the piston
pin 16. The piston 15 reciprocates inside the bore 12. By the reciprocating motion
of the piston 15, a refrigerant gas is led to the inside of the sealed container 1
through the suction tube 20, suctioned from the suction muffler 21 into the compression
chamber 13, and compressed inside the compression chamber 13 in succession.
[0013] According to the rotation of the crankshaft 7, the lubricating oil 2 is fed to the
slide sections by the oil feeding pump 10, and lubricates each of the slide sections.
In addition, the lubricating oil 2 serves to seal a gap formed between the piston
15 and the bore 12.
[0014] The main shaft section 8 of the crankshaft 7 and the bearing section 14 perform a
rotation. While the refrigerant compressor is stopped, a rotational speed is 0m/s.
During start-up of the refrigerant compressor, the rotation starts in a state in which
the metals are in contact with each other, and a great frictional resistance force
is generated. In this refrigerant compressor, the phosphate coating film is provided
on the main shaft section 8 of the crankshaft 7, and has an initial conformability.
In this structure, the phosphate coating film can prevent an abnormal abrasion caused
by the contact between the metals during start-up of the refrigerant compressor.
[0015] Patent Literature 2 discloses a refrigerant compressor according to the preamble
of claim 1.
[0016] Patent Literature 3 discloses a steel wire rod in which scale (oxide coating film)
is hard to detach during cooling, storage or transportation, and scale detachment
properties are excellent in mechanical descaling.
Citation List
Patent Literature
[0017]
Patent Literature 1: Japanese-Laid Open Patent Application Publication No. Hei. 7-238885
Patent Literature 2: European Patent Application Publication No. 2 818 716 A1
Patent Literature 3: European Patent Application Publication No. 2 113 580 A1
Summary of Invention
Technical Problem
[0018] In recent years, to provide higher efficiency of the refrigerant compressor, the
lubricating oil 2 with a lower viscosity is used, or a slide length of the slide sections
(a distance for which the slide sections slide) is designed to be shorter. For this
reason, the conventional phosphate coating film is likely to be abraded or worn out
at earlier time and it may be difficult to maintain the conformability between the
slide surfaces. As a result, the abrasion resistance of the phosphate coating film
may be degraded.
[0019] In the refrigerant compressor, while the crankshaft 7 is rotating once, a load applied
to the main shaft section 8 of the crankshaft 7 is significantly changed. With this
change in the load, the refrigerant gas dissolved into the lubricating oil 2 is evaporated
into bubbles, in a region between the crankshaft 7 and the bearing section 14. The
bubbles cause an oil film to run out, and the contact between the metals occurs more
frequently.
[0020] As a result, the phosphate coating film provided on the main shaft section 8 of the
crankshaft 7 is likely to be abraded at earlier time and a friction coefficient is
likely to be increased. With the increase in the friction coefficient, the slide section
generates more heat, and thereby abnormal abrasion such as adhesion may occur. A similar
phenomenon may occur in the region between the piston 15 and the bore 12. Therefore,
the piston 15 and the bore 12 have the same problem as that occurring in the crankshaft
7.
[0021] The present invention has been developed to solve the above described problem associated
with the prior art, and an object of the present invention is to provide a refrigerant
compressor which can improve an abrasion resistance of a slide member, to realize
high reliability and high efficiency, and a refrigeration device including the refrigerant
compressor.
Solution to Problem
[0022] To achieve the above-described object, there is provided a refrigerant compressor
which reserves lubricating oil in a sealed container, and accommodates therein an
electric component, and a compression component which is driven by the electric component
and compresses a refrigerant, wherein at least one of slide members included in the
compression component is made of an iron-based material, and wherein an oxide coating
film is provided on a slide surface of the iron-based material, the oxide coating
film comprising: a composition
A portion containing diiron trioxide (Fe
2O
3) which is more in quantity than other substances; a composition
B portion containing triiron tetraoxide (Fe
3O
4) which is more in quantity than other substances and containing a silicon (Si) compound;
and a composition
C portion containing triiron tetraoxide (Fe
3O
4) which is more in quantity than other substances and containing silicon (Si) which
is more in quantity than silicon (Si) of the composition
B portion, wherein the oxide coating film comprises at least an outermost portion which
is the composition A portion, an intermediate portion which is the composition B portion,
and an inner portion which is the composition C portion, the outermost portion, the
intermediate portion, and the inner portion being arranged in this order from an outermost
surface of the oxide coating film.
[0023] In accordance with this configuration, the abrasion resistance of the slide member
can be improved (increased), and the adhesivity of the oxide coating film can be improved.
This makes it possible to prevent abnormal abrasion (adhesion abrasion) which would
occur due to, for example, adhesion between the slide members constituting the slide
sections. Therefore, the viscosity of lubricating oil can be reduced, and the slide
length of slide members (a distance for which the slide members slide) constituting
the slide sections can be designed to be shorter. Since a sliding loss of the slide
section can be reduced, the refrigerant compressor can improve reliability, efficiency,
and performance.
[0024] To solve the above-described problem, a refrigerant compressor of the present invention
comprises a refrigerant circuit including the refrigerant compressor having the above-described
configuration, a heat radiator, a pressure reducing unit, and a heat absorber, which
are annularly coupled to each other via a pipe.
[0025] In accordance with this configuration, the refrigeration device includes the refrigerant
compressor with higher efficiency. Therefore, electric power consumption of the refrigeration
device can be reduced, and energy saving can be realized.
[0026] The above and further objects, features and advantages of the present invention will
more fully be apparent from the following detailed description of preferred embodiments
with reference to accompanying drawings.
Advantageous Effects of Invention
[0027] The present invention has advantages in that with the above described configuration,
it becomes possible to provide a refrigerant compressor which can improve an abrasion
resistance of a slide member, to realize high reliability and high efficiency, and
a refrigeration device including the refrigerant compressor.
Brief Description of Drawings
[0028]
Fig. 1 is a schematic cross-sectional view of a refrigerant compressor according to
Embodiment 1 of the present disclosure.
Fig. 2A is a TEM (transmission electron microscope) image showing an example of a
result of TEM observation performed for an oxide coating film provided on a slide
member of the refrigerant compressor according to Embodiment 1. Figs. 2B to 2D are
element maps showing an example of a result of EDS analysis performed for the oxide
coating film of Fig. 2A.
Figs. 3A to 3C are EELS maps showing an example of a result of EELS analysis performed
for the oxide coating film of Embodiment 1. Figs. 3D to 3F are views of analysis corresponding
to the EELS maps of Figs. 3A to 3C, respectively.
Fig. 4A is an EELS map showing an example of a result of the EELS analysis performed
for the outermost portion of the oxide coating film according to Embodiment 1. Fig.
4B is a view showing analysis corresponding to the EELS map of Fig. 4A.
Figs. 5A to 5E are views of analysis showing an example of a result of EELS analysis
performed for the intermediate portion of the oxide coating film according to Embodiment
1.
Fig. 6 is a view of analysis showing an example of a result of the EELS analysis performed
for the inner portion of the oxide coating film according to Embodiment 1.
Fig. 7 is a view showing the abrasion amounts of discs in conjunction with the oxide
coating film according to Embodiment 1, after a ring on disc abrasion test is conducted.
Fig. 8 is a view showing the abrasion amounts of rings in conjunction with the oxide
coating film according to Embodiment 1, after the ring on disc abrasion test is conducted.
Fig. 9 is a TEM (transmission electron microscope) image showing an example of a result
of TEM observation performed for the oxide coating film according to Embodiment 1,
after a reliability test is conducted.
Fig. 10 is a schematic cross-sectional view of a refrigerant compressor according
to Embodiment 2 of the present disclosure.
Fig. 11A is a TEM (transmission electron microscope) image showing an example of a
result of of TEM observation performed for an oxide coating film according to Embodiment
2 of the present disclosure. Fig. 11B is an element map showing an example of a result
of EDS analysis performed for the oxide coating film of Fig. 11A. Fig. 11C is a view
of analysis showing an example of a result of the EELS analysis performed for the
oxide coating film of Fig. 11A or 11B.
Fig. 12 is a schematic view of a refrigeration device according to Embodiment 3 of
the present disclosure.
Fig. 13 is a schematic cross-sectional view of a conventional refrigerant compressor.
Description of Embodiments
[0029] According to the present disclosure, there is provided refrigerant compressor which
reserves lubricating oil in a sealed container, and accommodates therein an electric
component, and a compression component which is driven by the electric component and
compresses a refrigerant, wherein at least one of slide members included in the compression
component is made of an iron-based material, and wherein an oxide coating film is
provided on a slide surface of the iron-based material, the oxide coating film comprising:
a composition
A portion containing diiron trioxide (Fe
2O
3) which is more in quantity than other substances; a composition
B portion containing triiron tetraoxide (Fe
3O
4) which is more in quantity than other substances and containing a silicon (Si) compound;
and a composition
C portion containing triiron tetraoxide (Fe
3O
4) which is more in quantity than other substances and containing silicon (Si) which
is more in quantity than silicon (Si) of the composition
B portion, wherein the oxide coating film comprises at least an outermost portion which
is the composition A portion, an intermediate portion which is the composition B portion,
and an inner portion which is the composition C portion, the outermost portion, the
intermediate portion, and the inner portion being arranged in this order from an outermost
surface of the oxide coating film.
[0030] In accordance with this configuration, the abrasion resistance of the slide member
can be improved, and the adhesivity of the oxide coating film can be improved. This
makes it possible to prevent abnormal abrasion (adhesion abrasion) which would occur
due to, for example, adhesion between the slide members constituting the slide sections.
Therefore, the viscosity of lubricating oil can be reduced, and the slide length of
slide members (a distance for which the slide members slide) constituting the slide
sections can be designed to be shorter. Since a sliding loss of the slide section
can be reduced, the refrigerant compressor can improve reliability, efficiency and
performance.
[0031] In the refrigerant compressor having the above-described configuration, the oxide
coating film comprises at least the outermost portion which is the composition
A portion, the intermediate portion which is the composition
B portion, and the inner portion which is the composition
C portion, the outermost portion, the intermediate portion, and the inner portion being
arranged in this order from the outermost surface.
[0032] In this configuration, since the composition
A portion is located in the outermost surface of the slide member, the outermost surface
contains more diiron trioxide (Fe
2O
3) which is relatively hard and flexible in crystal structure. This makes it possible
to suppress the attacking characteristic of the slide member with respect to the other
member and improve conformability at an initial stage of sliding. As a result, reliability
of the refrigerant compressor can be improved.
[0033] In the refrigerant compressor having the above-described configuration, the oxide
coating film may be provided on a surface of a base material made of the iron-based
material, and the composition
A portion may contain the silicon (Si) compound.
[0034] In this configuration, a number of silicon (Si) compounds such as silicon oxides
which are very hard are present in the composition
A portion. This makes it possible to form the oxide coating film which is more firm
(stronger) while maintaining the advantages obtained by diiron trioxide (Fe
2O
3) contained in the composition
A portion such that diiron trioxide (Fe
2O
3) is more in quantity than other substances. Therefore, even in a case where the slide
members slide under a sliding condition in which a load is high, the refrigerant compressor
can maintain high reliability.
[0035] In the refrigerant compressor having the above-described configuration, the silicon
(Si) compound contained in the oxide coating film may be at least one of silicon dioxide
(SiO
2) and fayalite (Fe
2SiO
4).
[0036] In this configuration, at least any one of the composition
A portion, the composition
B portion, and the composition
C portion contains a harder region. This makes it possible to further improve (increase)
the abrasion resistance of the oxide coating film, and improve the adhesivity between
the iron-based material (base material) and the oxide coating film. As a result, the
oxide coating film provided on the surface of the slide member can have a higher bearing
force, and hence reliability of the refrigerant compressor can be improved.
[0037] In the refrigerant compressor having the above-described configuration, the oxide
coating film may have a thickness in a range of 1 to 5µm.
[0038] In this configuration, since the abrasion resistance of the oxide coating film can
be improved, long-time reliability of the oxide coating film can be improved. In addition,
since dimension accuracy of the oxide coating film can be stabilized, productivity
of the slide member can be increased.
[0039] In the refrigerant compressor having the above-described configuration, the iron-base
material may contain 0.5 to 10% silicon.
[0040] In this configuration, since the adhesivity of the oxide coating film to the iron-based
material (base material) can be further improved, the bearing force of the oxide coating
film can be further increased. As a result, reliability of the refrigerant compressor
can be further improved.
[0041] In the refrigerant compressor having the above-described configuration, the iron-based
material may be cast iron.
[0042] Since cast iron is inexpensive and has a high productivity, cost of the slide member
can be reduced. Since the adhesivity of oxide coating film to the iron-based material
(base material) can be further improved, the bearing force of the oxide coating film
can be further increased. As a result, reliability of the refrigerant compressor can
be further improved.
[0043] In the refrigerant compressor having the above-described configuration, the refrigerant
may be a HFC-based refrigerant such as R134a, or a mixed refrigerant of the HFC-based
refrigerant, and the lubricating oil may be one of ester oil, alkylbenzene oil, polyvinyl
ether, and polyalkylene glycol, or mixed oil including any of ester oil, alkylbenzene
oil, polyvinyl ether, and polyalkylene glycol.
[0044] Even in a case where the lubricating oil with a low viscosity is used, an abnormal
abrasion of the slide member can be prevented. In addition, a sliding loss of the
slide member can be reduced. Therefore, reliability and efficiency of the refrigerant
compressor can be improved.
[0045] In the refrigerant compressor having the above-described configuration, the refrigerant
may be a natural refrigerant such as R600a, R290, or R744, or a mixed refrigerant
including any of the natural refrigerants, and the lubricating oil may be one of mineral
oil, ester oil, alkylbenzene oil, polyvinyl ether, and polyalkylene glycol, or mixed
oil including any of mineral oil, ester oil, alkylbenzene oil, polyvinyl ether, and
polyalkylene glycol.
[0046] Even in a case where the lubricating oil with a low viscosity is used, an abnormal
abrasion of the slide member can be prevented. In addition, a sliding loss of the
slide member can be reduced. Therefore, reliability and efficiency of the refrigerant
compressor can be improved. Further, by use of the refrigerant which produces less
greenhouse effect, global warming can be suppressed.
[0047] In the refrigerant compressor having the above-described configuration, the refrigerant
may be a HFO-based refrigerant such as R1234yf, or a mixed refrigerant of the HFO-based
refrigerant, and the lubricating oil may be one of ester oil, alkylbenzene oil, polyvinyl
ether, and polyalkylene glycol, or mixed oil including ester oil, alkylbenzene oil,
polyvinyl ether, and polyalkylene glycol.
[0048] Even in a case where the lubricating oil with a low viscosity is used, an abnormal
abrasion of the slide member can be prevented. In addition, a sliding loss of the
slide member can be reduced. Therefore, reliability and efficiency of the refrigerant
compressor can be improved. Further, by use of the refrigerant which produces less
greenhouse effect, global warming can be suppressed.
[0049] In the refrigerant compressor having the above-described configuration, the electric
component may be inverter-driven at one of a plurality of operating frequencies.
[0050] During a low-speed operation (running) in which oil is not sufficiently fed to the
slide sections, the oxide coating film with a high abrasion resistance can improve
reliability. Also, during a high-speed operation (running) in which the rotational
speed of the electric component increases, the oxide coating film with a high abrasion
resistance can maintain high reliability. As a result, reliability of the refrigerant
compressor can be further improved.
[0051] A refrigeration device according to the present disclosure comprises a refrigerant
circuit including the refrigerant compressor having the above-described configuration
, a heat radiator, a pressure reducing unit, and a heat absorber, which are annularly
coupled to each other via a pipe.
[0052] In accordance with this configuration, the refrigeration device includes the refrigerant
compressor with higher efficiency. Therefore, electric power consumption of the refrigeration
device can be reduced, and energy (power) saving can be realized. Further, reliability
of the refrigeration device can be improved.
[0053] Now, typical embodiments of the present disclosure will be described with reference
to the drawings. Throughout the drawings, the same or corresponding components (members)
are designated by the same reference symbols, and will not be described in repetition.
(Embodiment 1)
[Configuration of Refrigerant Compressor]
[0054] Firstly, a typical example of the refrigerant compressor according to Embodiment
1 will be specifically described with reference to Figs. 1 and 2A. Fig. 1 is a cross-sectional
view of a refrigerant compressor 100 according to Embodiment 1. Fig. 2A is a microscope
photograph showing an example of a result of TEM (transmission electron microscope)
observation performed for a slide member of the refrigerant compressor 100.
[0055] As shown in Fig. 1, in the refrigerant compressor 100, a refrigerant gas 102 comprising
R134a is filled inside a sealed container 101, and ester oil as lubricating oil 103
is reserved in the bottom portion of the sealed container 101. Inside the sealed container
101, an electric component 106 including a stator 104 and a rotor 105, and a reciprocating
compression component 107 configured to be driven by the electric component 106 are
accommodated.
[0056] The compression component 107 includes a crankshaft 108, a cylinder block 112, a
piston 132, and the like. The configuration of the compression component 107 will
be described below.
[0057] The crankshaft 108 includes at least a main shaft section 109 to which the rotor
105 is pressingly secured, and an eccentric shaft 110 which is provided eccentrically
with the main shaft section 109. An oil feeding pump 111 is provided at the lower
end of the crankshaft 108 and is in communication with the lubricating oil 103.
[0058] The crankshaft 108 comprises a base material 161 made of gray cast iron (FC cast
iron) containing about 2% silicon (Si), and an oxide coating film 160 provided on
a surface of the base material 161. Fig. 2A shows a typical example of the oxide coating
film 160 of Embodiment 1. Fig. 2A shows an example of a result of TEM (transmission
electron microscopy) observation performed for the cross-section of the oxide coating
film 160 and shows the image of whole of the oxide coating film 160 in a thickness
direction.
[0059] As shown in Fig. 2A, the oxide coating film 160 according to Embodiment 1 includes
an outermost portion 160a as a first layer, an intermediate portion 160b as a second
layer, and an inner portion 160c as a third layer, the outermost portion 160a, the
intermediate portion 160b, and the inner portion 160c being arranged in this order
from the outermost surface of the slide surface. The outermost portion 160a is a composition
A portion containing diiron trioxide (Fe
2O
3) which is more in quantity than other substances. The intermediate portion 160b is
a composition
B portion containing triiron tetraoxide (Fe
3O
4) which is more in quantity than other substances and containing the silicon (Si)
compound. The inner portion 160c is a composition
C portion containing triiron tetraoxide (Fe
3O
4) which is more in quantity than other substances and containing silicon (Si) which
is more in quantity than that of the composition
B portion.
[0060] The oxide coating film 160 according to Embodiment 1 has a thickness of about 2µm.
The oxide coating film 160 of Fig. 2A is formed on a disc (base material 161) used
in a ring on disc abrasion test in Example 1 which will be described later.
[0061] The cylinder block 112 comprises cast iron. The cylinder block 112 is formed with
a bore 113 with a substantially cylindrical shape, and includes a bearing section
114 supporting the main shaft section 109.
[0062] The rotor 105 is provided with a flange surface 120. The upper end surface of the
bearing section 114 is a thrust surface 122. A thrust washer 124 is disposed between
the flange surface 120 and the thrust surface 122 of the bearing section 114. The
flange surface 120, the thrust surface 122, and the thrust washer 124 constitute a
thrust bearing 126.
[0063] The piston 132 is loosely fitted into the bore 113 with a clearance. The piston 132
comprises an iron-based material. The piston 132 forms a compression chamber 134 together
with the bore 113. The piston 132 is coupled to the eccentric shaft 110 via a connecting
rod 138 as a coupling means by use of a piston pin 137. The end surface of the bore
113 is closed by a valve plate 139.
[0064] A head 140 constitutes a high-pressure chamber. The head 140 is secured to the valve
plate 139 on a side opposite to the bore 113. A suction tube (not shown) is secured
to the sealed container 101 and connected to a low-pressure side (not shown) of a
refrigeration cycle. The suction tube leads the refrigerant gas 102 to the inside
of the sealed container 101. A suction muffler 142 is retained between the valve plate
139 and the head 140.
[0065] The operation of the refrigerant compressor 100 configured as described above will
be described below.
[0066] Electric power supplied from a power supply utility (not shown) is supplied to the
electric component 106, and rotates the rotor 105 of the electric component 106. The
rotor 105 rotates the crankshaft 108. An eccentric motion of the eccentric shaft 110
is transmitted to the piston 132 via the connecting rod 138 as the coupling means
and the piston pin 137, and drives the piston 132. The piston 132 reciprocates inside
the bore 113. The refrigerant gas 102 led to the inside of the sealed container 101
through the suction tube (not shown) is suctioned from the suction muffler 142, and
is compressed inside the compression chamber 134.
[0067] According to the rotation of the crankshaft 108, the lubricating oil 103 is fed to
slide sections by the oil feeding pump 111. The lubricating oil 103 lubricates the
slide sections and seals the clearance between the piston 132 and the bore 113. The
slide sections are defined as sections (portions) which slide in a state in which
a plurality of slide members are in contact with each other in their slide surfaces.
[0068] In recent years, to provide higher efficiency of the refrigerant compressor 100,
for example, (1) lubricating oil with a lower viscosity is used as the lubricating
oil 103 as described above, or (2) the slide length of the slide members (a distance
for which the slide members slide) constituting the slide sections is designed to
be shorter. For this reason, slide conditions are getting more harsh. Specifically,
there is a tendency that the oil film formed between the slide sections is thinner,
or difficult to form.
[0069] In addition to the above, in the refrigerant compressor 100, the eccentric shaft
110 of the crankshaft 108 is provided eccentrically with the bearing section 114 of
the cylinder block 112, and the main shaft section 109 of the crankshaft 108. In this
layout, a fluctuating (variable) load which causes a load fluctuation (change) is
applied to regions between the main shaft section 109 of the crankshaft 108, the eccentric
shaft 110 and the connecting rod 138, due to a gas pressure of the compressed refrigerant
gas 102. With the load fluctuation (change), the refrigerant gas 102 dissolved into
the lubricating oil 103 is evaporated into bubbles in repetition, in, for example,
the region between the main shaft section 109 and the bearing section 114. In this
way, the bubbles are generated in the lubricating oil 103.
[0070] For the above-described reasons, for example, in the slide sections of the main shaft
section 109 of the crankshaft 108 and the bearing section 114, the oil film has run
out, and the metals of the slide surfaces contact each other more frequently.
[0071] However, the slide section of the refrigerant compressor 100, for example, the slide
section of the crankshaft 108 as an example of Embodiment 1 comprises the oxide coating
film 160 having the above-described configuration. For this reason, even if the oil
film has run out more frequently, the abrasion of the slide surface caused by this
can be suppressed over a long period of time.
[Configuration of Oxide Coating Film]
[0072] Next, the oxide coating film 160 which can suppress the abrasion of the slide section
will be described in more detail with reference to Figs. 2B to 6, in addition to Fig.
2A.
(Result of EDS Analysis)
[0073] Firstly, the concentration distribution of the elements of the oxide coating film
160 will be described with reference to Figs. 2A to 2D. Figs. 2B to 2D are element
maps showing an example of a result of EDS (energy dispersive X-ray spectrometry)
analysis performed for the cross-section of the oxide coating film 160 of Fig. 2A.
Fig. 2B shows the result of element mapping of iron (Fe) of the oxide coating film
160. Fig. 2C shows the result of element mapping of oxygen (O) of the oxide coating
film 160. Fig. 2D shows the result of element mapping of silicon (Si) of the oxide
coating film 160.
[0074] In Embodiment 1, the crankshaft 108 comprises the base material 161 made of gray
cast iron (FC cast iron). The oxide coating film 160 is formed on the surface of the
base material 161. Specifically, for example, the slide surface of the base material
161 is subjected to polishing finish, and then the oxide coating film 160 is formed
by oxidation by use of an oxidation gas.
[0075] As described above, in Embodiment 1, as shown in Fig. 2A, the oxide coating film
160 is formed on the base material 161 (on the right side of the base material 161
of Fig. 2A) made of gray cast iron (FC cast iron). It is clearly observed that the
oxide coating film 160 has a three-portion structure (three-layer structure) including
the outermost portion 160a (first layer), the intermediate portion 160b (second layer),
and the inner portion 160c (third layer), the outermost portion 160a, the intermediate
portion 160b, and the inner portion 160c being arranged in this order from the outermost
surface, as described above. In addition, it is observed that a white portion 160d
is present in a part of the intermediate portion 160b as the second layer.
[0076] Next, the concentrations of the elements contained in the oxide coating film 160
(namely, element composition of the portions of the oxide coating film 160) will be
described with reference to Figs. 2B to 2D. Fig. 2B shows the result of element mapping
of iron (Fe) of the oxide coating film 160. Fig. 2C shows the result of element mapping
of oxygen (O) of the oxide coating film 160. Fig. 2D shows the result of element mapping
of silicon (Si) of the oxide coating film 160. Figs. 2B to 2D show concentration ratios
of the elements by contrasting density of black and white. As the color of the image
is brighter, the ratio of the corresponding element is higher.
[0077] In Fig. 2A and Figs. 2B to 2D, a region surrounded by a pair of broken lines is the
oxide coating film 160, the left side is the base material 161, and the right side
is the outermost surface. As described above, the thickness of the oxide coating film
160 is about 2µm. Boundaries of the outermost portion 160a, the intermediate portion
160b, and the inner portion 160c are indicated by dot-and-dash lines.
[0078] From the result of the element analysis, it was found out that concentration ratios
of iron (Fe), oxygen (O), and silicon (Si) of the oxide coating film 160 have the
following trends.
[0079] Initially, the trend of the concentration distribution of iron (Fe) will be described
with reference to the element mapping result of iron (Fe) of Fig. 2B. As shown in
Fig. 2B, over the whole of the oxide coating film 160 (about 2µm from the surface
of the base material 161), a region in which iron (Fe) concentration is lower than
that of the base material 161 is formed. Therefore, of course, the concentration of
iron (Fe) of the oxide coating film 160 containing the iron oxidation product is lower
than that of the base material 161 which is the iron-based material.
[0080] In the inside of the oxide coating film 160, there is no significant concentration
difference (difference in contrasting density of black and white), in the iron (Fe)
concentration distribution in a direction from the outermost surface toward the base
material 161. From this, it can be seen that iron (Fe) is basically uniformly distributed
in the inside of the oxide coating film 160. As shown in Fig. 2B, in a portion corresponding
to the above-described white portion 160d, in the inside of the oxide coating film
160, the iron (Fe) concentration is reduced.
[0081] Then, the trend of the concentration distribution of oxygen (O) will be described
with reference to the element mapping result of oxygen (O) of Fig. 2C. As shown in
Fig. 2C, over the whole of the oxide coating film 160 (about 2µm from the surface
of the base material 161), a region in which oxygen (O) concentration is much higher
than that of the base material 161 is formed. It is observed that this oxygen (O)
concentration distribution and the iron (Fe) concentration distribution of 2B are
formed in almost the same region. Therefore, a portion containing the iron oxidation
product as a major component, which is different from the base material 161 as the
iron-based material, is formed in the oxide coating film 160.
[0082] Regarding the oxygen (O) concentration distribution of the whole of the oxide coating
film 160, a significant concentration difference in the whole region from the outermost
surface toward the base material 161 is not observed, as in the iron (Fe) concentration
distribution. From this, it can be seen that oxygen (O) is basically uniformly distributed
in the inside of the oxide coating film 160, as in iron (Fe). As shown in Fig. 2C,
in a portion corresponding to the above-described white portion 160d, in the inside
of the oxide coating film 160, the oxygen (O) concentration is reduced, as in iron
(Fe).
[0083] Then, the trend of the concentration distribution of silicon (Si) will be described
with reference to the element mapping result of silicon (Si) of Fig. 2D. As shown
in Fig. 2D, the silicon (Si) concentration of the base material 161 is high, and the
silicon (Si) concentration of the inner portion 160c of the oxide coating film 160
which is closer to the base material 161 is high. In contrast, the silicon (Si) concentration
in an interface between the inner portion 160c and the intermediate portion 160b is
significantly reduced.
[0084] A portion corresponding to the above-described white portion 160d, of the intermediate
portion 160b, the silicon (Si) concentration is increased. In the example of Fig.
2D, in the outermost portion 160a, silicon (Si) is not substantially observed.
[0085] From the element mapping results of Figs. 2B to 2D, in the oxide coating film 160,
the elements which are iron (Fe) and oxygen (O) are present over the whole region
from the outermost portion 160a to the inner portion 160c. However, in the outermost
portion 160a, silicon (Si) is not substantially present or less. Also, it is observed
that in a part of the intermediate portion 160b and most of the inner portion 160c,
silicon (Si) is present.
(Result of EELS Analysis)
[0086] Next, the states of the elements of iron (Fe), oxygen (O), and silicon (Si) will
be described more specifically with reference to Figs. 3A to 3F. Figs. 3A to 3C show
results of element mapping obtained by EELS (electron energy loss spectroscopy) analysis
performed for a part of the cross-section of the oxide coating film 160 of Fig. 2A.
Figs. 3D to 3F are views of analysis corresponding to the EELS waveforms of Figs.
3A to 3C, respectively.
[0087] The EELS analysis is a method in which the composition or combined state of a sample
is analyzed and evaluated, by measuring energy lost by a mutual action between an
electron and an atom when the electron is transmitted through the sample. By the EELS
analysis, a particular energy waveform associated with the element or electron structure
of the sample can be obtained.
[0088] Fig. 3D is an analysis view showing the EELS waveform (mesh region of Fig. 3D) of
iron (Fe), of a region of the cross-section of the oxide coating film 160. Fig. 3A
shows the element mapping result of iron (Fe) of the region corresponding to Fig.
3D. Fig. 3E is an analysis view showing the EELS waveform (mesh region of Fig. 3E)
of oxygen (O), of a region of the cross-section of the oxide coating film 160. Fig.
3B shows the element mapping result of oxygen (O) of the region corresponding to Fig.
3E. Fig. 3F is an analysis view showing the EELS waveform (mesh region of Fig. 3F)
of silicon (Si), of a region of the cross-section of the oxide coating film 160. Fig.
3C shows the element mapping result of silicon (Si) of the region corresponding to
Fig. 3F.
[0089] Figs. 3A to 3C show the intensities of the EELS waveforms by contrasting density
of black and white. As the color of the image is brighter, the ratio of the corresponding
EELS waveform is higher.
[0090] From the results of the EELS analysis, the intensities of the EELS waveforms (hereinafter
will be simply referred to as "waveform intensities") of iron (Fe), oxygen (O), and
silicon (Si) of the oxide coating film 160 have the following trends.
[0091] Initially, from the result of the EELS analysis of iron (Fe) of Figs. 3A and 3D,
the waveform intensity of iron (Fe) will be described. As shown in Fig. 3A, in the
inside of the oxide coating film 160, there is no significant intensity difference
in the distribution of the waveform intensity of iron (Fe), from the outermost surface
(left side in Fig. 3A) toward the base material 161 (right side in Fig. 3A). From
this, it can be seen that iron (Fe) is uniformly distributed over the oxide coating
film 160. In a part corresponding to the above-described white portion 160d, the waveform
intensity of iron (Fe) is reduced.
[0092] Then, from the result of the EELS analysis of oxygen (O) of Figs. 3B and 3E, the
waveform intensity of oxygen (O) will be described. As shown in Fig. 3B, in the inside
of the oxide coating film 160, there is no significant intensity difference in the
distribution of the waveform intensity of oxygen (O), from the outermost surface (left
side in Fig. 3B) toward the base material 161 (right side in Fig. 3B), as in the case
of iron (Fe). From this, it can be seen that oxygen (O) is uniformly distributed over
the oxide coating film 160, and the oxide coating film 160 entirely comprises iron
oxidation product. In a part corresponding to the above-described white portion 160d,
the waveform intensity of oxygen (O) is reduced.
[0093] Then, from the result of the EELS analysis of silicon (Si) of Figs. 3C and 3F, the
waveform intensity of silicon (Si) will be described. As shown in Fig. 3C, the waveform
intensity of silicon (Si) is high in a region (right side in Fig. 3C) which is closer
to the base material 161 (right side in Fig. 3C), and is reduced toward the outermost
surface (right side in Fig. 3C). The waveform intensity of silicon (Si) is reduced,
in the interface between the inner portion 160c and the intermediate portion 160b
of the oxide coating film 160 (see Fig. 2D). In a part of the intermediate portion
160b, corresponding to the above-described white portion 160d, the waveform intensity
of silicon (S) is increased.
[0094] From the results of EELS analysis of Figs, 3A to 3F, in the oxide coating film 160,
the elements which are iron (Fe) and oxygen (O) are present over the whole region
from the outermost portion 160a to the inner portion 160c, as in the results of EDS
analysis (element mapping results) of Figs. 2B to 2D. However, in the outermost portion
160a, silicon (Si) is not substantially present or less. Also, it is observed that
in a part of the intermediate portion 160b and most of the inner portion 160c, silicon
(Si) is present.
(Result of EELS Analysis of Portions of Oxide Coating Film)
[0095] Next, the specific configuration of the oxide coating film 160 will be described
by further performing the EELS analysis for the outermost portion 160a, the intermediate
portion 160b, and the inner portion 160c of the oxide coating film 160. Specifically,
the intensity distributions of iron (Fe), oxygen (O), and silicon (Si), and the states
of these elements, of the portions of the oxide coating film 160, will be described
more specifically with reference to Figs. 4A to 6.
[0096] Fig. 4B is an analysis view showing an enlarged waveform of a portion corresponding
to iron (Fe), of the EELS waveform of the outermost portion 160a of the oxide coating
film 160. Fig. 4A shows the result of element mapping of iron (Fe), which conforms
to a peak of the enlarged waveform of Fig. 4B, in the cross-section of the oxide coating
film 160. The EELS waveform of Fig. 4B is a typical waveform of diiron trioxide (Fe
2O
3).
[0097] Fig. 3A shows the result of element mapping of the whole of iron (Fe). In Fig. 4A,
the intensity distribution of ion (Fe) is not seen. In contrast, as shown in Fig.
4A, the image of the portion which is closer to the outermost surface (left side in
Fig. 4A), namely, the outermost portion 160a, is brightest, and therefore the waveform
intensity of diiron trioxide (Fe
2O
3) is very high. From this, it is seen that the outermost portion 160a contains diiron
trioxide (Fe
2O
3) which is more in quantity than other substances.
[0098] Fig. 5A is an analysis view showing an enlarged waveform of a portion corresponding
to iron (Fe), of the EELS waveform of the intermediate portion 160b of the oxide coating
film 160. The EELS waveform of Fig. 5A is a typical waveform of triiron tetraoxide
(Fe
3O
4). Regarding a portion of the intermediate portion 160b, which is other than the portion
corresponding to Fig. 5A, the EELS waveform similar to that of Fig. 5A is observed.
Therefore, the intermediate portion 160b contains triiron tetraoxide (Fe
3O
4) which is more in quantity than other substances.
[0099] Figs. 5B and 5C are analysis views showing enlarged waveforms of the same portion
corresponding to oxygen (O), of the EELS waveform of the white portion 160d included
in the intermediate portion 160b. Fig. 5B shows a peak at a location that is closer
to 525eV. Fig. 5C shows no peak. The peak at a location that is closer to 525eV is
unique to the iron oxidation product. Therefore, it can be seen that oxygen (O) is
not bonded to iron (Fe), in a measurement portion of the enlarged waveform of Fig.
5C, namely, the white portion 160d.
[0100] Figs. 5D and 5E are analysis views showing enlarged waveforms of the same portion
corresponding to silicon (Si), of the EELS waveform of the white portion 160d included
in the intermediate portion 160b. Figs. 5B and 5C, and Figs. 5D and 5E show the EELS
waveforms of the same portion. Figs. 5D and 5E show almost the same EELS waveform.
Therefore, in the white portion 160d, silicon (Si) is bonded to oxygen (O).
[0101] From a comparison between the EELS waveforms of Figs. 5B and 5C, and the EELS waveforms
of Figs. 5D and 5E, it is seen that oxygen (O) which is not bonded to iron (Fe) and
bonded to silicon (Si), and oxygen (O) bonded to iron (Fe) and silicon (Si) are present
in the white portion 160d included in the intermediate portion 160b. Therefore, plural
kinds of silicon (Si) compounds having different structures, such as silicon dioxide
(SiO2) and fayalite (Fe2SiO4) are present in the white portion 160d.
[0102] Further, the enlarged waveform of the portion corresponding to iron (Fe), of the
EELS waveform of a black portion of the inner portion 160c of the oxide coating film
160 has substantially the same shape as that of the enlarged waveform of Fig. 5A,
although this is not shown. Therefore, it is seen that the inner portion 160c contains
triiron tetraoxide (Fe
3O
4) which is more in quantity than other substances, as in the intermediate portion
160b.
[0103] Fig. 6 is an analysis view showing an enlarged waveform of a portion corresponding
to silicon (Si), of the EELS waveform of the inner portion 160c of the oxide coating
film 160. The shape of EELS waveform of Fig. 6 is different from those of the EELS
waveform of Fig. 5D and the EELS waveform of Fig. 5E. From the EELS waveform of Fig.
6, in this portion, silicon (Si) is not bonded to oxygen (O). This implies that solid-solved
silicon (Si) is present (silicon (Si) is present as elemental substances) in this
portion. The waveform similar to the EELS waveform of Fig. 5B and the EELS waveform
of Fig. 5D is observed in another portion of the inner portion 160c. Therefore, the
silicon (Si) compound and solid-solved silicon (Si) portion are present in the inner
portion 160c, as in the intermediate portion 160b.
[0104] As described above, the oxide coating film 160 according to the present disclosure
includes three portions which are different from each other in composition, which
are the composition
A portion, the composition
B portion, and the composition
C portion. Among these, the composition
A portion is, for example, the outermost portion 160a containing diiron trioxide (Fe
2O
3) which is more in quality than other substances. The composition
B portion is, for example, the intermediate portion 160b containing triiron tetraoxide
(Fe
3O
4) which is more in quality than other substances and containing the silicon (Si) compound.
The composition
C portion contains triiron tetraoxide (Fe
3O
4) which is more in quality than other substances and contains silicon (Si) which is
more in quantity than that of the composition
B portion.
[0105] As described above, the oxide coating film 160 includes at least the outermost portion
160a as the composition
A portion, the intermediate portion 160b as the composition
B portion, and the inner portion 160c as the composition
C portion, the outermost portion 160a, the intermediate portion 160b, and the inner
portion 160c being arranged in this order from the outermost surface.
[0106] The oxide coating film 160 may include portions which are different in composition
from the composition
A portion, the composition
B portion, and the composition
C portion, so long as it includes the composition
A portion, the composition
B portion, and the composition
C portion.
[0107] As typical example of the conditions, there is a manufacturing method (formation
method) of the oxide coating film 160. As the manufacturing method of the oxide coating
film 160, a known oxidation method of an iron-based material may be suitably used.
The manufacturing method of the oxide coating film 160 is not limited. Manufacturing
conditions or the like can be suitably set, depending on the conditions which are
the kind of the iron-based material which is the base material 161, its surface state
(the above-described polishing finish, etc.), desired physical property of the oxide
coating film 160, or the like. In the present disclosure, the oxide coating film 160
can be formed on the surface of the base material 161 by oxidating gray cast iron
as the base material 161 within a range of several hundreds degrees C, for example,
within a range of 400 to 800 degrees C, by use of a known oxidation gas such as a
carbon dioxide gas and known oxidation equipment.
[Evaluation of Oxide Coating Film]
[0108] Next, regarding a typical example of the oxide coating film 160 according to Embodiment
1, a result of evaluation of the characteristic of the oxide coating film 160 will
be described with reference to Figs. 7 to 9. Hereinafter, the abrasion suppressing
effect of the oxide coating film 160, namely, the abrasion resistance of the oxide
coating film 160 will be evaluated, based on results of Example, Prior Art Example,
and Comparative Example.
(Example 1)
[0109] As the slide member, a disc made of gray cast iron was used. The base material 161
was gray cast iron. The surface of the disc was the slide surface. As described above,
the disc was oxidated within a range of 400 to 800 degrees C, by use of the oxidation
gas such as the carbon dioxide gas, to form the oxide coating film 160 according to
Embodiment 1 on the slide surface. As shown in Figs. 2A to 4, the oxide coating film
160 included a first portion 151, a second portion 152, and a third portion 153. In
this way, evaluation sample of Example 1 was prepared. The abrasion resistance of
the evaluation sample and attacking characteristic of the evaluation sample with respect
to the other member (sliding between the evaluation sample and the other member occurred)
were evaluated as will be described later.
(Prior Art Example 1)
[0110] As a surface treatment film, the conventional phosphate coating film was formed instead
of the oxide coating film 160 according to Embodiment 1. Except this, the evaluation
sample of Prior Art Example 1 was prepared as in Example 1. The abrasion resistance
of the evaluation sample and attacking characteristic of the evaluation sample with
respect to the other member (sliding between the evaluation sample and the other member
occurred) were evaluated as will be described later.
(Comparative Example 1)
[0111] As a surface treatment film, a gas nitride coating film which is generally used as
a hard film was formed instead of the oxide coating film 160 according to Embodiment
1. Except this, the evaluation sample of Comparative Example 1 was prepared as in
Example 1. The abrasion resistance of the evaluation sample and attacking characteristic
of the evaluation sample with respect to the other member (sliding between the evaluation
sample and the other member occurred) were evaluated as will be described later.
(Comparative Example 2)
[0112] As a surface treatment film, a conventional general oxide coating film, triiron tetraoxide
(Fe
3O
4) single portion coating film was formed by a method called black oxide coating (fellmight
treatment), instead of the oxide coating film 160 according to Embodiment 1. Except
this, the evaluation sample of Comparative Example 2 was prepared as in Example 1.
The abrasion resistance of the evaluation sample and attacking characteristic of the
evaluation sample with respect to the other member (sliding between the evaluation
sample and the other member occurred) were evaluated as will be described later.
(Evaluation of Abrasion Resistance and Attacking Characteristic with Respect to the
Other Member)
[0113] The ring on disc abrasion test was conducted on the above-described evaluation samples
in a mixture ambience including T134a refrigerant and ester oil with VG3 (viscosity
grade at 40 degrees C was 3mm
2/s). In addition to discs as the evaluation samples, rings each including a base material
made of gray cast iron and having a surface (slide surface) having been subjected
to the surface polish, were prepared as the other members (sliding between the evaluation
sample and the other member occurred). The abrasion test was conducted under a condition
of a load 1000N, by use of intermediate pressure CFC friction/abrasion test machine
AFT-18-200M (product name) manufactured by A&D Company, Limited. In this way, the
abrasion resistance of the surface treatment film formed on the evaluation sample
(disc) and the attacking characteristic of the surface treatment film with respect
to the slide surface of the other member (ring) (sliding between the evaluation sample
and the other member occurred) were evaluated.
(Comparison Among Example 1, Prior Art Example 1, Comparative Example)
[0114] Fig. 7 shows a result of the ring on disc abrasion test and shows the abrasion amounts
of the slide surfaces of the discs as the evaluation samples. Fig. 8 shows a result
of the ring on disc abrasion test and shows the abrasion amounts of the rings as the
other members.
[0115] Initially, comparison will be made for the abrasion amounts of the surfaces (slide
surfaces) of the discs as the evaluation samples. As shown in Fig. 7, the abrasion
amounts of the surfaces of the discs were less in the surface treatment films of Example
1, Comparative Example 1, and Comparative Example 2 than in the phosphate coating
film of Prior Art Example 1. From this, it was found out that the surface treatment
films of Example 1, Comparative Example 1, and Comparative Example 2 had good abrasion
resistances. However, it was found out that regarding the surface treatment film (general
oxide coating film) of Comparative Example 2, containing triiron tetraoxide (Fe
3O
4) single portion, several portions of the surface of the disc were peeled from the
interface with the base material.
[0116] Then, comparison will be made for the abrasion amounts of the surfaces (slide surfaces)
of the rings as the other members (sliding between the evaluation sample and the other
member occurred), with reference to Fig. 8. The abrasion amount of the surface of
the ring corresponding to the surface treatment film of Example 1, namely, the oxide
coating film 160 according to Embodiment 1 was almost equal to that of the phosphate
coating film of Prior Art Example 1. In contrast, it was observed that the abrasion
amounts of the surfaces of the rings corresponding to the gas nitride coating film
of Comparative example 1, and the general oxide coating film of Comparative example
2 were more than those of Example 1 and Prior Art Example 1. From these results, it
was found out that the attacking characteristic of the oxide coating film 160 according
to Embodiment 1 with respect to the other member was less as in the general phosphate
coating film.
[0117] As should be understood from the above, the abrasions of the disc and the ring, corresponding
to only Example 1 including the oxide coating film 170 according to the present disclosure
were not substantially observed. Thus, it was found out that the oxide coating film
170 according to the present disclosure had favorable abrasion resistance and attacking
characteristic.
[0118] The abrasion resistance of the oxide coating film 160 will be discussed. Since the
oxide coating film 160 is the iron oxidation product, the oxide coating film 160 is
very chemically stable compared to the conventional phosphate coating film. In addition,
the coating film of the iron oxidation product has a hardness higher than that of
the phosphate coating film. By forming the oxide coating film 160 on the slide surface,
generation, adhesion, or the like of abrasion powder can be effectively prevented.
As a result, the increase in the abrasion amount of the oxide coating film 160 can
be effectively avoided.
[0119] Next, the attacking characteristic of the oxide coating film 160 with respect to
the other member will be discussed. The outermost portion 160a of the oxide coating
film 160 includes the composition
A portion. The composition
A portion contains diiron trioxide (Fe
2O
3) which is more in quantity than other substances. Therefore, the composition
A portion can suppress the attacking characteristic of the oxide coating film 160 with
respect to the other member, and improve the conformability of the slide surface,
for the reasons stated below.
[0120] The crystal structure of diiron trioxide (Fe
2O
3) which is the major component of the composition
A portion is rhombohedral crystal. The crystal structure of triiron tetraoxide (Fe
3O
4) is cubical crystal. The crystal structure of the nitride coating film is hexagonal
close-packed crystals, face-centered cubical crystals, and body-centered tetragonal
crystals. For this reason, diiron trioxide (Fe
2O
3) is flexible (or weak) in the crystal structure compared to triiron tetraoxide (Fe
3O
4) or the nitride coating film. Therefore, the outermost portion 160a as the composition
A portion has a low hardness in the particle (grain) level.
[0121] The composition
A portion containing much diiron trioxide (Fe
2O
3) has a hardness in grain (particle) level lower than that of the gas nitride coating
film of Comparative Example 1 or the general coating film (triiron tetraoxide (Fe
3O
4) single portion coating film) of Comparative Example 2. Therefore, the oxide coating
film 160 of Example 1 can effectively suppress the attacking characteristic with respect
to the other member and improve the conformability of the slide surface, compared
to the surface treatment film of Comparative Example 1 or the surface treatment film
of Comparative Example 2.
[0122] Although in the ring on disc abrasion test of Embodiment 1, the test was conducted
in a state in which the disc was provided with the oxide coating film, the same effects
can be obtained by providing the oxide coating film on the ring. The evaluation method
of the abrasion resistance of the oxide coating film is not limited to the ring on
disc abrasion test, and another test method may be used.
(Example 2)
[0123] Next, a device reliability test was conducted on the refrigerant compressor 100 including
the crankshaft 108 provided with the oxide coating film 160 according to Embodiment
1 to confirm the advantages of the oxide coating film 160. The refrigerant compressor
100 has the configuration of Fig. 1 as described above, which will not be described
in repetition. In the device reliability test, as in the above-described Example 1,
or the like, R134a refrigerant and ester oil with VG3 (viscosity grade at 40 degrees
C was 3mm
2/s) were used. To accelerate the abrasion of the main shaft section 109 of the crankshaft
108, the refrigerant compressor 100 was operated in a high-temperature high-load intermittent
operation mode in which operation (running) and stopping of the refrigerant compressor
100 were repeated under a high-temperature state.
[0124] After the device reliability test was finished, the refrigerant compressor 100 was
disassembled, the crankshaft 108 was taken out, and the slide surface of the crankshaft
108 was checked. Based on a result of the observation of the slide surface, evaluation
of the device reliability test was conducted.
[0125] Fig. 9 shows a result of a TEM (transmission electron microscope)image obtained by
TEM observation performed for the cross-section of a region that is in the vicinity
of the slide surface of the crankshaft 108, after the device reliability test was
conducted. As shown in Fig. 9, in the cross-section of a region that is in the vicinity
of the slide surface, the oxide coating film 160 was formed on the base material 161
(on the right side of the base material 161) made of gray cast iron (FC cast iron).
After the device reliability test was conducted, it was confirmed that the oxide coating
film 160 had a three-portion structure including the outermost portion 160a, the intermediate
portion 160b, and the inner portion 160c, and the states of these portions were not
changed.
[0126] Based on the result of Example 1 and Example 2, consideration will be given to the
fact that the oxide coating film 160 including the outermost portion 160a (composition
A portion), the intermediate portion 160b (composition
B portion), and the inner portion 160c (composition
C portion) can obtain advantages.
[0127] As can be clearly seen from the above-described result of the ring on disc abrasion
test (result of Example 1), the outermost portion 160a (composition
A portion) contains diiron trioxide (Fe
2O
3) as a major component. The crystal structure of diiron trioxide (Fe
2O
3) is flexible in the crystal structure, compared to triiron tetraoxide (Fe
3O
4) or the nitride coating film. Therefore, the oxide coating film 160 including the
outermost portion 160a can effectively suppress the attacking characteristic with
respect to the other member (sliding between the slide member provided with the oxide
coating film 160 and the other member occurred)and improve the conformability of the
slide surface, as described above.
[0128] As can be clearly seen from the result of the device reliability test (result of
Example 2), the abrasion of the oxide coating film 160 was not observed after the
device reliability test. From this, the abrasion resistance of the oxide coating film
160 is high in practical use. It is considered that the outermost portion 160a (composition
A portion) of the oxide coating film 160 can improve the abrasion resistance.
[0129] One of physical properties (characteristics) which are directly related to the abrasion,
of the surface treatment film of the slide member, is hardness. The hardness of diiron
trioxide (Fe
2O
3) which is a major component of the outermost portion 160a is about 537Hv. In contrast,
the hardness of triiron tetraoxide (Fe
3O
4) which is a major component of the conventional general oxide coating film is about
420Hv. Thus, the hardness of diiron trioxide (Fe
2O
3) is higher than that of triiron tetraoxide (Fe
3O
4). From this, it is estimated that the oxide coating film 160 of Example 1 has in
an outremost surface thereof a portion (outermost portion 160a) having a higher abrasion
resistance than the general oxide coating film (triiron tetraoxide (Fe
3O
4) single portion coating film) of Comparative Example 2.
[0130] The intermediate portion 160b and the inner portion 160c contain the silicon (si)
compound. Generally, the silicon (Si) compound has a hardness higher than that of
the general iron oxidation product. Therefore, it is estimated that even in a case
where the outermost portion 160a is abraded, the intermediate portion 160b and the
inner portion 160c have a higher abrasion resistance than the conventional general
oxide coating film (triiron tetraoxide (Fe
3O
4) single portion coating film of Comparative Example 2).
[0131] The oxide coating film 160 has higher adhesivity to the base material 161 (iron-based
material) than the conventional general oxide coating film. It is presumed that a
cause of improved adhesivity (bearing force) of the oxide coating film 160 is as follows.
[0132] For example, in
Kobe Steel, Ltd Technical Report Vol. 1.55 (No. 1 Apr. 2005), it is recited that (1) the oxide coating film (scaling) is generated on the surface
of a steel plate in a hot rolling step of an iron/steel material, and (2) descaling
characteristic reduces as the amount of silicon contained in the iron/steel material
increases. These recitations suggest that an oxide product containing silicon and
iron can improve the adhesivity of the oxide coating film onto the surface of the
iron-based material.
[0133] The oxide coating film 160 of Example 1 includes the intermediate portion 160b as
the underlayer of the outermost portion 160a, and the inner portion 160c as the underlayer
of the intermediate portion 160b. The intermediate portion 160b is the composition
B portion. The inner portion 160c is the composition
C portion. It is considered that the composition
B portion and the composition
C portion containing the silicon (Si) compound can improve the adhesivity to the base
material 161, of the oxide coating film 160 including the outermost portion 160a.
The inner portion 160c which is the composition
C portion contains silicon which is more in quantity than that of the composition
B portion. Since the portion containing the silicon (Si) compound is provided and the
content of silicon in the region of the oxide coating film 160 which is closer to
the base material 161, is high, the adhesive force of the oxide coating film 160 can
be further improved. As a result, the bearing force of the oxide coating film 160
with respect to a load during sliding is improved, and thus peeling of the oxide coating
film 160 is effectively prevented.
[0134] As described above, the composition
C portion which is the inner portion 160c may include solid-solved silicon (Si) portion
as elemental substances, as well as the silicon (Si) compound. It is expected that
the solid-solved silicon (Si) portion can improve the adhesivity of the oxide coating
film 160. The solid-solved silicon (Si) portion can be present in a localized region
of the intermediate portion 160b (composition
B portion) as well as the inner portion 160c (composition
C portion), by setting conditions. This can improve the mutual adhesivity between the
portions. Therefore, the advantages similar to the above-described advantages can
be obtained, or more advantages can be obtained.
[Modification, etc.]
[0135] In Embodiment 1, the sealed container 101 reserves therein the lubricating oil 103,
accommodates therein the electric component 106 and the compression component 107
which is driven by the electric component 106 and compresses the refrigerant, at least
one slide member included in the compression component 107 comprises the iron-based
material, and the oxide coating film 160 including the composition
A portion, the composition
B portion, and the composition
C portion is provided on the slide surface of this iron-based material.
[0136] The composition
A portion of the oxide coating film 160 contains Fe
2O
3 which is more in quantity than other substances. The composition
B portion of the oxide coating film 160 contains triiron tetraoxide (Fe
3O
4) which is more in quantity than other substances. The composition
B portion also contains the silicon (Si) compound and may contain the solid-solved
silicon (Si) portion. The composition
C portion of the oxide coating film 160 contains triiron tetraoxide (Fe
3O
4) which is more in quantity than other substances, and contains silicon which is more
in quantity than that of the composition
B portion. For example, the composition
C portion may contain the silicon (Si) compound and the solid-solved silicon (Si) portion.
Or, the composition
C portion may contain the silicon (Si) compound and may not contain the solid-solved
silicon (Si) portion.
[0137] By forming the oxide coating film 160 on the slide surface of the slide member, the
abrasion resistance of the slide member is improved, and the adhesivity of the oxide
coating film 160 (the bearing force of the oxide coating film 160) to the base material
161 is improved. Since a sliding loss in the slide section can be reduced, reliability,
efficiency and performance of the refrigerant compressor 200 can be improved.
[0138] The silicon (Si) compound of the present disclosure is not limited to the silicon
oxidation product such as silicon dioxide (SiO
2), or silicate salt such as fayalite (Fe
2SiO
4) and means a compound containing silicon in a chemical structure. Further, the silicon
(Si) compound of the present disclosure includes a state in which silicon enters a
region between crystal lattices formed by other elements. Therefore, the silicon (Si)
compound of the present disclosure is not intended to define its molecular state.
The silicon (Si) compound of the present disclosure is defined as a compound including
silicon, or inorganic composition including silicon in its structure. Therefore, the
silicon (Si) compound of the present disclosure can also be expressed as "silicon
composition".
[0139] Although the thickness of the oxide coating film 160 is about 2µm in Embodiment 1,
the thickness of the oxide coating film 160 is not limited to this. Typically, the
thickness of the oxide coating film 160 may be in a range of 1 to 5µm. In a case where
the thickness of the oxide coating film 160 is less than 1 µm, it is difficult for
the oxide coating film 160 to maintain the characteristic such as the abrasion resistance
over a long period of time, depending on the condition. On the other hand, in a case
where the thickness of the oxide coating film 160 is more than 5µm, surface roughness
of the slide surface becomes excess depending on the conditions. Therefore, in some
cases, it is difficult to control accuracy of the slide sections constituted by the
plurality of slide members.
[0140] Although gray cast iron is used as the base material 161 in Embodiment 1, the material
of the base material 161 is not limited to this. The specific structure of the base
material 161 provided with the oxide coating film 160 is not particularly limited
so long as it is the iron-based material. Typically, cast iron is suitably used as
the base material 161, and the iron-based material is not limited to the cast iron.
The base material 161 may be a steel material, a sintered material, or other iron-based
materials. Also, the specific kind of the cast iron is not particularly limited, and
may be gray cast iron (cast iron, FC cast iron) as described above, spherical graphite
cast iron (FCD cast iron) or other cast irons.
[0141] Commonly, gray cast iron contains about 2% silicon. The content of silicon of the
base material 161 is not particularly limited. In a case where the iron-based material
contains silicon, the adhesivity of the oxide coating film 160 can be improved in
some cases. In general, the cast iron contains about 1 to 3% silicon. Therefore, for
example, spherical graphite cast iron (FCD cast iron) can be used as the base material
161. Commonly, the steel material or the sintered material does not substantially
contain silicon, or the content of silicon of the steel material or the sintered material
is lower than that of the cast iron. About 0.5 to 10% silicon may be added to the
steel material or the sintered material. This makes it possible to obtain advantages
similar to those in a case where the cast iron is used as the base material 161.
[0142] The state of the surface of the base material 161 on which the oxide coating film
160 is formed, namely, the slide surface, is not particularly limited. Typically,
the surface of the base material 161 is the polished surface. However, the surface
of the base material 161 may be an unpolished surface or a surface having been subjected
to a known surface treatment before the oxidation, depending on the kind of the base
material 161, the kind of the slide member, or the like.
[0143] Although in Embodiment 1, R134a is used as the refrigerant, the kind of the refrigerant
is not limited to this. Although in Embodiment 1, the ester oil is used as the lubricating
oil 103, the kind of the lubricating oil 103 is not limited to this. Known refrigerant
and lubricating oil may be suitably used as combinations of the refrigerant and the
lubricating oil 103.
[0144] Suitable combinations of the refrigerant and the lubricating oil 103 are, for example,
three examples described below. By using these combinations, high efficiency and reliability
of the refrigerant compressor 100 can be achieved as in Embodiment 1.
[0145] In an example of combination 1, R134a, another HFC-based refrigerant, or HFC-based
mixed refrigerant is used as the refrigerant, and ester oil, alkylbenzene oil, polyvinyl
ether, polyalkylene glycol, or mixed oil including any of ester oil, alkylbenzene
oil, polyvinyl ether, and polyalkylene glycol may be used as the lubricating oil 103.
[0146] In an example of combination 2, natural refrigerant such as R600a, R290, or R744,
or mixed refrigerant including any of the natural refrigerants is used as the refrigerant,
and one of mineral oil, ester oil, alkylbenzene oil, polyvinyl ether, and polyalkylene
glycol, or mixed oil including any of mineral oil, ester oil, alkylbenzene oil, polyvinyl
ether, and polyalkylene glycol may be used as the lubricating oil 103.
[0147] In an example of combination 3, HFO- based refrigerant such as R1234yf or mixed refrigerant
of HFO-based refrigerants is used as the refrigerant, and one of ester oil, alkylbenzene
oil, polyvinyl ether, and polyalkylene glycol, or mixed oil including any of ester
oil, alkylbenzene oil, polyvinyl ether, and polyalkylene glycol may be used as the
lubricating oil 103.
[0148] Among the above-described combinations, the combination 2 or 3 can suppress global
warming by use of the refrigerant which produces less greenhouse effect. In the combination
3, a group of the lubricating oil 103 may further include mineral oil.
[0149] Although in Embodiment 1, the refrigerant compressor 100 is the reciprocating refrigerant
compressor as described above, the refrigerant compressor of the present disclosure
is not limited to the reciprocating refrigerant compressor, and is applicable to other
compressors, such as a rotary refrigerant compressor, a scroll refrigerant compressor,
or a vibrational refrigerant compressor. The refrigerant compressor to which the present
disclosure is applicable can obtain advantages similar to those of Embodiment 1 so
long as it has a known configuration including the slide sections, discharge valves,
others.
[0150] Although in Embodiment 1, the refrigerant compressor 100 is driven by the power supply
utility, the refrigerant compressor according to the present disclosure is not limited
to this, and may be inverter-driven at any one of a plurality of operating frequencies.
By forming the oxide coating film 160 having the above-described configuration on
the slide surface of the slide section included in the refrigerant compressor which
is inverter-driven at any one of a plurality of operating frequencies, the abrasion
resistance of the slide member can be increased, and the bearing force of the oxide
coating film 160 (adhesivity of the oxide coating film 160 to the base material 161)
can be increased. This makes it possible to improve reliability of the refrigerant
compressor even during a low-speed operation (running) in which the oil is not sufficiently
fed to the slide sections, or during a high-speed operation (running) in which the
rotational speed of the electric component increases.
(Embodiment 2)
[0151] In Embodiment 1 described above, as a preferable example, the oxide coating film
160 includes the composition
A portion, the composition
B portion, and the composition
C portion, and the composition
A portion substantially contains diiron trioxide (Fe
2O
3). The present disclosure is not limited to this. In Embodiment 2, the composition
A portion contains the silicon (Si) compound or the like. This will be described specifically.
[Configuration of Refrigerant Compressor]
[0152] Initially, a typical example of a refrigerant compressor according to Embodiment
2 will be specifically described with reference to Figs. 10 and 11A. Fig. 10 is a
cross-sectional view of a refrigerant compressor 200 according to Embodiment 2. Fig.
11A is a TEM (transmission electron microscope) image showing an example of a result
of TEM observation performed for the cross-section of an oxide coating film 260.
[0153] As shown in Fig. 10, in the refrigerant compressor 200, a refrigerant gas 102 comprising
R134a is filled inside a sealed container 201, and ester oil as lubricating oil 103
is reserved in the bottom portion of the sealed container 201. Inside the sealed container
201, an electric component 106 including a stator 104 and a rotor 105, and a reciprocating
compression component 207 configured to be driven by the electric component 106 are
accommodated.
[0154] The compression component 207 includes a crankshaft 208, a cylinder block 112, a
piston 132, and the like. The configuration of the compression component 207 will
be described below.
[0155] The crankshaft 208 includes at least a main shaft section 209 to which the rotor
105 is pressingly secured, and an eccentric shaft 210 which is provided eccentrically
with the main shaft section 209. An oil feeding pump 211 is provided at the lower
end of the crankshaft 208 and is in communication with the lubricating oil 103. The
crankshaft 208 comprises base material 261 made of gray cast iron (FC cast iron) containing
about 2% silicon (Si), and the oxide coating film 260 provided on a surface of the
base material 261.
[0156] The cylinder block 112 comprises cast iron. The cylinder block 112 is formed with
a bore 113 with a substantially cylindrical shape, and includes a bearing section
114 supporting the main shaft section 209.
[0157] The rotor 105 is provided with a flange surface 120. The upper end surface of the
bearing section 114 is a thrust surface 122. A thrust washer 124 is disposed between
the flange surface 120 and the thrust surface 122 of the bearing section 114. The
flange surface 120, the thrust surface 122, and the thrust washer 124 constitute a
thrust bearing 126.
[0158] The piston 132 is loosely fitted into the bore 113 with a clearance. The piston 132
comprises an iron-based material. The piston 132 forms a compression chamber 134 together
with the bore 113. The piston 132 is coupled to the eccentric shaft 110 via a connecting
rod 138 as a coupling means by use of a piston pin 137. The end surface of the bore
113 is closed by a valve plate 139.
[0159] A head 140 constitutes a high-pressure chamber. The head 140 is secured to the valve
plate 139 on a side opposite to the bore 113. A suction tube (not shown) is secured
to the sealed container 201 and connected to a low-pressure side (not shown) of a
refrigeration cycle. The suction tube leads the refrigerant gas 102 to the inside
of the sealed container 201. A suction muffler 142 is retained between the valve plate
139 and the head 140.
[0160] The operation of the refrigerant compressor 200 configured as described above will
be described below.
[0161] Electric power supplied from a power supply utility (not shown) is supplied to the
electric component 106, and rotates the rotor 105 of the electric component 106. The
rotor 105 rotates the crankshaft 208. An eccentric motion of the eccentric shaft 210
is transmitted to the piston 132 via the connecting rod 138 as the coupling means
and the piston pin 137, and drives the piston 132. The piston 132 reciprocates inside
the bore 113. The refrigerant gas 102 led to the inside of the sealed container 201
through the suction tube (not shown) is suctioned from the suction muffler 142, and
is compressed inside the compression chamber 134.
[0162] According to the rotation of the crankshaft 208, the lubricating oil 103 is fed to
slide sections by the oil feeding pump 211. The lubricating oil 103 lubricates the
slide sections and seals the clearance between the piston 132 and the bore 113.
[0163] In recent years, to provide higher efficiency of the refrigerant compressor 200,
for example, (1) lubricating oil with a lower viscosity is used as the lubricating
oil 103 as described above, or (2) the slide length of the slide sections (a distance
for which the slide sections slide) is designed to be shorter. For this reason, slide
conditions are getting more harsh. Specifically, there is a tendency that the oil
film formed between the slide sections is thinner, or difficult to form.
[0164] In addition to the above, in the refrigerant compressor 200, the eccentric shaft
210 of the crankshaft 208 is provided eccentrically with the bearing section 114 of
the cylinder block 112, and the main shaft section 209 of the crankshaft 208. In this
layout, a fluctuating (variable) load which causes a load fluctuation (change) is
applied to regions between the main shaft section 209 of the crankshaft 208, the eccentric
shaft 210 and the connecting rod 138, due to a gas pressure of the compressed refrigerant
gas 102. With the load fluctuation (change), the refrigerant gas 102 dissolved into
the lubricating oil 103 is evaporated into bubbles in repetition, in, for example,
the region between the main shaft section 209 and the bearing section 114. In this
way, the bubbles are generated in the lubricating oil 103.
[0165] For the above-described reasons, for example, in the slide sections of the main shaft
section 209 of the crankshaft 208 and the bearing section 114, the oil film has run
out, and the metals of the slide surfaces contact each other more frequently.
[0166] However, the slide section of the refrigerant compressor 200, for example, the slide
section of the crankshaft 208 as an example of Embodiment 2 comprises the oxide coating
film 260 having the above-described configuration (see Fig. 11A). For this reason,
even if the oil film has run out more frequently, the abrasion of the slide surface
caused by this can be suppressed over a long period of time.
[Configuration of Oxide Coating Film]
[0167] Next, the oxide coating film 260 according to Embodiment 2 which is provided on the
slide section will be described in more detail with reference to Figs. 11A to 11C.
Fig. 11A is the TEM (transmission electron microscope) image showing a result of the
TEM observation performed for the cross-section of the oxide coating film 260. Fig.
11B shows a result of element mapping of EDS analysis performed for the cross-section
of the oxide coating film 260 of Fig. 11A. Fig. 11C is a view showing a result of
the EELS analysis performed for the cross-section of the oxide coating film 260 of
Fig. 11A.
[0168] In Embodiment 2, the crankshaft 208 comprises a base material 261 which is gray cast
iron (FC cast iron). The oxide coating film 260 is provided on the surface of the
base material 261. As in Embodiment 1, specifically, for example, the slide surface
of the base material 261 is subjected to polishing finish, and then the oxide coating
film 260 is formed by oxidation by use of an oxidation gas.
[0169] As described above, as shown in Fig. 11A, in Embodiment 2, the oxide coating film
260 is formed on the base material 261 (not shown). It is clearly observed that the
oxide coating film 260 according to Embodiment 3 has a three-portion structure (three-layer
structure) including the outermost portion 260a (first layer), the intermediate portion
260b (second layer), and the inner portion 260c (third layer), the outermost portion
260a, the intermediate portion 260b, and the inner portion 260c being arranged in
this order from the outermost surface of the oxide coating film 260, as described
above.
[0170] The outermost portion 260a is the composition
A portion containing diiron trioxide (Fe
2O
3) which is more in quantity than other substances, as in the outermost portion 160a
according to Embodiment 1. The intermediate portion 260b is the composition
B portion containing triiron tetraoxide (Fe
3O
4) which is more in quantity than other substances and containing the silicon (Si)
compound, as in the intermediate portion 160b according to Embodiment 1. The inner
portion 260c is the composition
C portion containing triiron tetraoxide (Fe
3O
4) which is more in quantity than other substances, and containing silicon which is
more in quantity than that of the composition
B portion, as in the inner portion 160c according to Embodiment 1.
[0171] Next, the concentration of silicon (Si) contained in the oxide coating film 260 will
be described with reference to Figs. 11B and 11C. As described above, Fig. 11B shows
a result of element mapping of silicon (Si) corresponding to the oxide coating film
260 of Fig. 11A. Fig. 11B shows the concentration ratio of silicon (Si) by contrasting
density of black and white. As the color of the image is brighter, the ratio of silicon
(Si) is higher. In the example of Figs. 11A and 11B, the thickness of the oxide coating
film 260 is about 2.5µm. Boundaries of the outermost portion 260a, the intermediate
portion 260b, and the inner portion 260c of the oxide coating film 260 are indicated
by dot-and-dash lines.
[0172] From the results of the element analysis, as shown in Fig. 11B, the silicon (Si)
concentration of the base material 261 is high, and the silicon (Si) concentration
of the inner portion 260c of the oxide coating film 260 which is closer to the base
material 261 is high. In contrast, in the interface between the inner portion 260c
and the intermediate portion 260b, the silicon (Si) concentration is significantly
reduced.
[0173] As in the white portion 160d of the intermediate portion 160b according to Embodiment
1, a white portion 260d is present in the intermediate portion 260b. In a region corresponding
to the white portion 260d, as shown in Fig. 11B, the silicon (Si) concentration is
increased. Silicon (Si) in the outermost portion 160a according to Embodiment 1 was
not substantially observed. As shown in Fig. 11B, it is observed that in Embodiment
2, the white portion 260e is present in the outermost portion 260a. It is observed
that the silicon (Si) concentration in a region corresponding to the white portion
260e is increased.
[0174] Fig. 11C shows EELS waveforms of regions corresponding to regions indicated by numbers
1-4 in Fig. 11A. From the results of analysis for silicon (Si) of the oxide coating
film 260, these EELS waveforms indicate that in the oxide coating film 260, silicon
(Si) bonded to oxygen (O) is present in these regions. It can be seen that in the
oxide coating film 260, the silicon (Si) compound such as silicon dioxide (SiO
2) is present in the outermost portion 260a (e.g., region indicated by 1 and 2 in Figs.
11A and 11C) in addition to the inner portion 260c (e.g., region indicated by 4 in
Figs. 11A and 11C), and the intermediate portion 260b (e.g., region indicated by 3
in Figs. 11A and 11C).
[0175] The results of analysis for iron (Fe) and oxygen (O) of the oxide coating film 260
are similar to those of the oxide coating film 160 according to Embodiment 1, although
this is not described in Embodiment 2.
[0176] Therefore, in the oxide coating film 260 according to Embodiment 2, the white portion
260e is present in the outermost portion 260a, and the silicon (Si) compound is present
in the white portion 260e.
[0177] Next, consideration will be given to the fact that the oxide coating film 260 according
to Embodiment 2 can obtain advantages because it includes the outermost portion 260a
(composition
A portion), the intermediate portion 260b (composition
B portion), and the inner portion 260c (composition
C portion), and the outermost portion 260a (composition
A portion) contains at least the silicon (Si) compound.
[0178] As described in Embodiment 1, the outermost portion 260a (composition
A portion) contains diiron trioxide (Fe
2O
3) as a major component. The crystal structure of diiron trioxide (Fe
2O
3) is flexible in the crystal structure, compared to triiron tetraoxide (Fe
3O
4) or the nitride coating film. Therefore, the oxide coating film 260 including the
outermost portion 260a can effectively suppress the attacking characteristic with
respect to the other member (sliding between the slide member provided with the oxide
coating film 260 and the other member occurs) and improve the conformability of the
slide surface, as described above. In addition, as described in Embodiment 1, the
outermost portion 260a (composition
A portion) of the oxide coating film 260 can improve the abrasion resistance of the
oxide coating film 260.
[0179] The intermediate portion 260b and the inner portion 260c contain the silicon (Si)
compound. As described in Embodiment 1, generally, the silicon (Si) compound has a
hardness higher than that of the iron oxidation product. Therefore, it is estimated
that even in a case where the outermost portion 260a is abraded, the intermediate
portion 260b and the inner portion 260c have a high abrasion resistance. As described
in Embodiment 1, the oxide coating film 260 has higher adhesivity (bearing force)
to the base material 261 (iron-based material) than the conventional general oxide
coating film.
[0180] In the oxide coating film 260 according to Embodiment 2, the outermost portion 260a
contains the silicon (Si) compound with a hardness higher than that of the iron oxidation
product. It is considered that this silicon (Si) compound contributes to suppressing
the abrasion of the outermost portion 260a. It is estimated that since the oxide coating
film 260 includes the outermost portion 260a containing the silicon (Si) compound,
it can have a higher abrasion resistance.
[0181] In Embodiment 2, as described above, the inner portion 260c (composition
C portion) may include solid-solved silicon (Si) portion as elemental substances, as
well as the silicon (Si) compound. It is expected that the solid-solved silicon (Si)
portion can improve the adhesivity of the oxide coating film 260. The solid-solved
silicon (Si) portion can be present in a localized region of the intermediate portion
260b (composition
B portion) or the outermost portion 260a (composition
A portion) as well as the inner portion 260c (composition
C portion), by setting conditions. This can improve the mutual adhesivity between the
portions. Therefore, the advantages similar to the above-described advantages can
be obtained, or more advantages can be obtained.
[0182] In Embodiment 2, the sealed container 201 reserves therein the lubricating oil 103,
accommodates therein the electric component 106 and the compression component 207
which is driven by the electric component 106 and compresses the refrigerant, at least
one slide member included in the compression component 207 comprises the iron-based
material, and the oxide coating film 160 including the composition
A portion, the composition
B portion, and the composition
C portion is provided on the slide surface of this iron-based material.
[0183] The composition
A portion of the oxide coating film 260 contains diiron trioxide (Fe
2O
3) which is more in quantity than other substances, and may contain the silicon (Si)
compound or the solid-solved silicon (Si) portion. The composition
B portion of the oxide coating film 260 contains triiron tetraoxide (Fe
3O
4) which is more in quantity than other substances. The composition
B portion contains the silicon (Si) compound and may contain the solid-solved silicon
(Si) portion. The composition
C portion of the oxide coating film 260 contains triiron tetraoxide (Fe
3O
4) which is more in quantity than other substances, and contains silicon which is more
in quantity than that of the composition
B portion. For example, the composition
C portion may contain the silicon (Si) compound and the solid-solved silicon (Si) portion.
Or, the composition
C portion may contain the silicon (Si) compound and may not contain the solid-solved
silicon (Si) portion.
[0184] By forming the oxide coating film 260 on the slide surface of the slide member, the
abrasion resistance of the slide member is improved, and the adhesivity of the oxide
coating film 260 (the bearing force of the oxide coating film 260) to the base material
261 is improved. In Embodiment 2, the silicon (Si) compound is present in the outermost
portion 260a which is the composition
A portion. Since the composition
A portion is located in the outermost portion of the slide surface, the slide surface
can have a high abrasion resistance just after the slide operation of the slide section
has started. This makes it possible to effectively suppress start-up failure such
as twist, which is likely to occur at re-start-up, when the refrigerant compressor
200 is operated intermittently.
(Embodiment 3)
[0185] In Embodiment 3, an example of a refrigeration (freezing) device including the refrigerant
compressor 100 of Embodiment 1 or the refrigerant compressor 200 of Embodiment 2 will
be specifically described with reference to Fig. 12.
[0186] Fig. 12 is a schematic view of a refrigeration device including the refrigerant compressor
100 according to Embodiment 1 or the refrigerant compressor 200 according to Embodiment
2. In Embodiment 3, only the schematic basic configuration of the refrigeration device
will be described.
[0187] As shown in Fig. 12, the refrigeration device according to Embodiment 3 includes
a body 375, a partition wall 378, a refrigerant circuit 370, and the like. The body
375 is formed by, for example, a heat insulating casing and doors. A surface of the
casing opens and the doors are provided to open and close the opening of the casing.
The inside of the body 375 is divided by the partition wall 378 into an article storage
space 376 and a mechanical room 377. Inside the storage space 376, a blower (not shown)
is provided. Alternatively, the inside of the body 375 may be divided into spaces
other than the storage space 376 and the mechanical room 377.
[0188] The refrigerant circuit 370 is configured to cool the inside of the storage space
376. The refrigerant circuit 370 includes, for example, the refrigerant compressor
100 of Embodiment 1, a heat radiator 372, a pressure reducing unit 373, and a heat
absorber 374 which are annularly coupled to each other by pipes. The heat absorber
374 is disposed in the storage space 376. Cooling heat of the heat absorber 374 is
agitated by the blower (not shown) and circulated through the inside of the storage
space 376 as indicated by broken-line arrows shown in Fig. 12. In this way, the inside
of the storage space 376 is cooled.
[0189] The refrigerant compressor 100 included in the refrigerant circuit 370 includes the
slide member made of the iron-based material, and the oxide coating film 160 is formed
on the slide surface of this slide member, as described in Embodiment 1. Instead of
the refrigerant compressor 100, the refrigerant circuit 370 may include the refrigerant
compressor 200 of Embodiment 2. The refrigerant compressor 200 includes the slide
member made of the iron-based material, and the oxide coating film 260 is formed on
the slide surface of this slide member, as in the refrigerant compressor 100.
[0190] As described above, the refrigeration device according to Embodiment 3 includes the
refrigerant compressor 100 according to Embodiment 1 (or the refrigerant compressor
200 according to Embodiment 2). The slide section included in the refrigerant compressor
100 (or the refrigerant compressor 200) can improve the abrasion resistance of the
slide member and the adhesivity (bearing force of the oxide coating film 160 or the
oxide coating film 260) of the oxide coating film 160 (or the oxide coating film 260)
to the base material 161 (or the base material 261). The refrigerant compressor 100
(or the refrigerant compressor 200) can reduce a sliding loss of the slide section,
and achieve high reliability and high efficiency. As a result, the refrigeration device
according to Embodiment 3 can reduce electric power consumption, and realize energy
saving.
[0191] Numerous modifications and alternative embodiments of the invention will be apparent
to those skilled in the art in view of the foregoing description. Accordingly, the
description is to be construed as illustrative only, and is provided for the purpose
of teaching those skilled in the art the best mode of carrying out the invention.
The details of the structure and/or function may be varied substantially without departing
from the scope of the appended claims.
Industrial Applicability
[0192] As described above, the present invention can provide a refrigerant compressor which
can obtain high reliability under a condition in which it uses lubricating oil with
a low viscosity, and a refrigeration device using this refrigerant compressor. Therefore,
the present invention is widely applicable to devices using refrigeration cycles.
Reference Signs List
[0193]
- 100
- refrigerant compressor
- 101
- sealed container
- 103
- lubricating oil
- 106
- electric component
- 107
- compression component
- 108
- crankshaft (slide member)
- 160
- oxide coating film
- 160a
- outermost portion
- 160b
- intermediate portion
- 160c
- inner portion
- 160d
- white portion
- 161
- base material
- 200
- refrigerant compressor
- 201
- sealed container
- 207
- compression component
- 208
- crankshaft (slide member)
- 260
- oxide coating film
- 260a
- outermost portion
- 260b
- intermediate portion
- 260c
- inner portion
- 260d
- white portion
- 260e
- white portion
- 370
- refrigerant circuit
- 372
- heat radiator
- 373
- pressure reducing unit
- 374
- heat absorber